In the case of an edge emitting semiconductor laser, radiation generated in an active layer of the semiconductor laser emerges from a semiconductor body of the edge emitting semiconductor laser in a direction parallel to the active layer. Since a semiconductor has a high refractive index, in principle, a large proportion of the emerging radiation is reflected back into the semiconductor body at the edge of the semiconductor laser, whereby the laser activity of the semiconductor laser is made possible. The reflection can be influenced by a surface coating of the edges of the semiconductor laser. For this purpose, the semiconductor laser has to be detached from a wafer assemblage in which a layer sequence of the semiconductor body is grown epitaxially. It is only then that the edges of the semiconductor laser are uncovered and their surface can be treated. Therefore, the surface treatment of the edges is in principle not carried out in the wafer assemblage. Furthermore, the edge emitting semiconductor lasers are in general not tested in the wafer assemblage.
Furthermore, in the case of the edge emitting semiconductor laser, the radiation emerges from the semiconductor body in an exit region at the active layer. Particularly in the case of a high intensity of the radiation and/or in the case of a long operating duration, this can promote wear, for example melting, of the active layer in the exit region. The melting is regularly referred to as COD (Catastrophic Optical Damage).